Unwanted water production is a major problem in maximizing the hydrocarbon production potential of a subterranean well. Tremendous costs may be incurred from separating and disposing of large amounts of produced water, inhibiting the corrosion of tubulars contacted by the water, replacing corroded tubular equipment downhole, and surface equipment maintenance. Shutting off unwanted water production is a necessary condition to maintaining a productive field.
Different methods and materials have been used to treat near-wellbore subterranean formations to selectively control unwanted water production in the oil industry. The goal is to maximize hydrocarbon production while minimizing and controlling the production of water. Pumping or squeezing certain materials, such as relative permeability modifiers (RPMs), into subterranean formations forms a water-blocking matrix within the formation to control the water flow while not affecting the flow of oil and/or gas therefrom. RPMs thus reduce the permeability of water relative to hydrocarbons such as oil and gas.
The permeability adjustment of the formation is sometimes referred to as water flow regulation, or more simply as water regulation. Water control and profile modification have been routinely performed using a variety of polymers, such as polyacrylamide, cellulose and xanthan gum.
The conventional manner of RPM applications for water control involves pumping the RPM into a formation matrix that is a highly heterogeneous porous media. Unfortunately, the RPM is hard to uniformly distribute, and it is easy to inadvertently generate formation damage in the formation matrix in the process.
It would thus be desirable to discover a method which could improve the control of unwanted water production from subsurface formations and improve distribution of the water control agent, while minimizing formation damage.